Linear stability analysis of flow in an open cavity with a back chamber

This paper focuses on investigating the influence of a back chamber on the flow stability in an open-cavity model. First, the global stability analysis employed in the study is introduced and validated, followed by a description of the open-cavity configuration equipped with a back chamber. Base flow computations reveal that the introduction of a back chamber leads to the formation of three vortex structures: a Primary Eddy, an UpStream Eddy, and a DownStream Eddy. The global stability analysis is employed to conduct investigations into the effects of two- and three-dimensional disturbances, Reynolds numbers, and the corresponding direct global eigenmodes. The study further examines the inviscid centrifugal instability mechanism responsible for triggering three-dimensional flow instability in the field. Furthermore, this study tries to relate the studied model to the compressor physics. On one hand, axial and radial momentum source terms are introduced into the flow field to investigate their effects on the downstream boundary layer. On the other hand, unsteady numerical simulations are conducted to examine the impact of upstream-propagating disturbances, caused by a subsonic compressor, on the incoming flow boundary layer. The results indicate that the influence of both models on the downstream boundary layer is essentially consistent. The introduction of a back chamber provides additional volume to dissipate the energy of the upstream-propagating disturbances.